New accurate two-noded shear-flexible curved beam elements

 There are two purposes of this work. One is to present two accurate two-noded finite elements which are derived from the potential energy principle and the Hellinger–Reissner functional principle respectively. The second is to show the successful application of the internal displacement parameters in developing a high-order related displacement-rotation interpolation field. Because the derived interpolation field is capable of accurately modeling deformation modes in extreme thin curved beams and nearly straight beams, both shear locking and membrane shocking are avoided. Several standard numerical tests display superior behaviors of the present elements. Received: 5 February 2002 / Accepted: 16 September 2002     

LXT384接口芯片的几种环回形式

LXT384是一个用于SONET/SDH设备的八进制T1/E1/J1线路接口单元芯片。文中简述了该芯片在实际应用中进行自检的若干种不同的环回形式(包括：模拟环回、数字环回、运程环回等)，直观地指出了各种环回形式的特点和区别。     

ST-102C式NaI(Tl)晶体中KX射线逃逸率的计算

本文对ST-102C式NaI(Tl)晶体中碘原子K层X射线的五种主要成分K_(α1)、K_(α2)、K_(β1)、K_(β2)和 K_(β3)的逃逸率分别进行了计算,然后根据五种 X 射线的相对强度进一步计算了加权平均逃逸率。计算中所选用的初始入射 X 射线能量在33.5—1000keV 之间。     

Detection of multiple cracks using frequency measurements

A method for detection of multiple open cracks in a slender Euler-Bernoulli beams is presented based on frequency measurements. The method is based on the approach given by Hu and Liang [J. Franklin Inst. 330 (5) (1993) 841], transverse vibration modelling through transfer matrix method and representation of a crack by rotational spring. The beam is virtually divided into a number of segments, which can be decided by the analyst, and each of them is considered to be associated with a damage parameter. The procedure gives a linear relationship explicitly between the changes in natural frequencies of the beam and the damage parameters. These parameters are determined from the knowledge of changes in the natural frequencies. After obtaining them, each is treated in turn to exactly pinpoint the crack location in the segment and determine its size. The forward, or natural frequency determination, problems are examined in the passing. The method is approximate, but it can handle segmented beams, any boundary conditions, intermediate spring or rigid supports, etc. It eliminates the need for any symbolic computation which is envisaged by Hu and Liang [J. Franklin Inst. 330 (5) (1993) 841] to obtain mode shapes of the corresponding uncracked beams. The proposed method gives a clear insight into the whole analysis. Case studies (numerical) are presented to demonstrate the method effectiveness for two simultaneous cracks of size 10% and more of section depth. The differences between the actual and predicted crack locations and sizes are less than 10% and 15% respectively. The numbers of segments into which the beam is virtually divided limits the maximum number of cracks that can be handled. The difference in the forward problem is less than 5%.     

等离子体浸没式离子注入-离子束增强沉积TiN膜研究

本文采用一种新型的等离子体浸没式离子注入 离子束增强沉积的技术(PIII IBAD),在Cr12MoV钢基体上制备出了TiN膜,对沉积膜的组织进行了光电子能谱分析,并对沉积膜进行了硬度检测、摩擦试验及磨痕形貌分析。试验结果表明,沉积膜中的组织为TiN、TiO2和Ti2O3,TiN膜具有高达Hv3200的高硬度和极其优良的摩擦性能。     

Surface chemistry of tribochemical reactions explored in ultrahigh vacuum conditions

The thermal decomposition of model extreme-pressure lubricant additives on clean iron was studied in ultrahigh vacuum conditions using molecular beam strategies. Methylene chloride and chloroform react to deposit a solid film consisting of FeCl₂ and carbon, and evolve only hydrogen into the gas phase. No gas-phase products and less carbon on the surface are detected in the case of carbon tetrachloride. Dimethyl and diethyl disulfide react on clean iron to deposit a saturated sulfur plus carbon layer at low temperatures (∼600 K) and an iron sulfide film onto a Fe + C underlayer at higher temperatures (∼950 K). Methane is the only gas-phase product when dimethyl disulfide reacts with iron. Ethylene and hydrogen are detected when diethyl disulfide is used.     

步进梁式炉的运动研究

对国内引进的、用于粉末冶金的步进梁式炉的运动,以图解法和解析法进行了分析,并对运动参数进行了理论推导和计算。本研究结果,对解决步进粱式炉的运动故障以及进行新型设计提供了有效的理论分析和计算依据。     

基于EWB的D/A数模转换器的仿真研究

阐述了D／A转换器的仿真原理，给出了T形电阻网络D／A转换器仿真模型的构造方法，并采用EWB进行了系统仿真，仿真结果表明该方法是合理、可行的。     

基于偏振光干涉仪的Interleaver解复用器实验研究

为实现更窄信道间隔的密集波分复用 ,提出了一种基于偏振光干涉仪的新型Interleaver解复用器 ,分析了结构组成与基本工作原理 ,对其进行了初步的测试实验 ,该器件所分开的DWDM系统两组波长功率均衡 ,隔离度分别为 1 0 6dB和 1 4 6 4dB ,- 1dB带宽分别为 0 7nm和 0 4nm。